DURING the war years, a greater emphasis has been placed on the control of pediculosis capitis. This increase in the interest in this infestation has been precepitated largely by the fact that as much as a tenfold increase in the condition has been noted and, too, because of the relationship of typhus fever to pediculosis. The increase in the crowding index of populations in the urban districts of war areas and the influx of peoples of all classes from many sections of the United States, as well as certain foreign countries, have contributed to this problem. The principal methods of control are prophylaxis and the treatment of those patients infested with the vermin. Personal cleanliness is the first prerequisite in the control of human lice infestation. It can hardly be questioned that at least weekly baths with warm water and soap, with frequent changes of clean clothing, would reduce the frequency of secondary' infestation. On the other hand, crowding and intermingling of population groups in dwellings, in industry, places of amusement, and aboard common carriers increase the risk of infestation. It is not unusual in a large, crowded community to see louse infestation among clean families. The control of pediculosis by treatment of the active cases has been very discouraging in the past, largely because the lousicides available were only of limited value and required a great deal of time and effort by the patients. The materials used and recommended were usually good or fairly good lousicides but would not destroy or loosen the nits. The destruction or removal of the nits was contingent upon secondary treatment with manual or mechanical removal. The tedious nature of such treatment can actually discourage even the most cooperative patient, and yet' adequate treatment is not possible without the removal of the nits, because these nits, unless destroyed or removed from the hair, will hatch in about 7 days, and the cycle of reinfestation is reestablished. The potentialities of such reinfestation can only be evaluated when one recognizes that each female louse is capable of laying 50 to 150 eggs, and that the average louse will live for a period of 30 to 40 days.